The two-year-old civil war in Syria has been brutal from the start and itís getting worse. Both sides have been accused of committing atrocities and the fighting has driven many thousands of civilians, caught between the two warring factions, to flee to crowded refugee camps in neighboring countries.

But the conflict became even more complicated this past week as any hopes that the fighting might be contained geographically vanished when Israel launched multiple missile strikes against targets inside Syria.

On Sunday, Israeli officials described the most recent attack, on a warehouse at the Damascus airport, as a move to neutralize an unacceptable ďgame changerĒ serving the needs of its own enemies. If nothing else the attack ó justified or not ó certainly changed the equation in the Middle East.

For President Obama, Israelís decision to launch missiles at targets within Syria only complicates an already grimly complex question (how the United States can best serve the Syrian rebel cause), although it may be that Obama can, or must, accept Israelís explanation that it was merely protecting itself by targeting Iranian missiles being shipped through Syria to Lebanon.

They believed, the Israelis explained, that the Iranian weapons inevitably would eventually be used against Israel by Hezbollah. Therefore, they argued, it became necessary to intervene.

Keep in mind that, to the leadership of both Iran and the militants who comprise Hezbollahís military and political organization, their hatred of Israel surpasses whatever affection or loyalty they may have for Assadís regime in Damascus.

The Sunday attack was Israelís second in two days and third this year. Although described as an act of self-defense, the attack also may have sent a signal that Israel intends to help the Syrian rebels, who lately have begun to suffer substantial losses as the Assad government has launched offensives around both the capital, Damascus, and the city of Homs to the north.

American intelligence sources identified the target of the first of the attacks, last Thursday, a shipment of ground-to-ground missiles. Believed to have been shipped from Iran, the missiles were described as highly accurate, solid-fuelled weapons capable of hitting Israelís main population centers, such as Tel Aviv, from southern Lebanon.

But American officials also admit itís not clear whether the missiles were intended for the Syrian army or for Hezbollah. However, since the airport warehouse is believed to have been under the control of personnel from Hezbollah and Iranís paramilitary Quds Force, Israelís fears seem justified.

The rebel Damascus Military Council, perhaps encouraged by the Israeli missile attack, on Sunday issued a statement calling on all the various anti-government rebel groups to put aside their rivalries and to focus their attacks on government forces protecting Damascus.

The existence of these rebel rivalries, reflecting the differing priorities of the various anti-Assad groups, has been a major factor in the reluctance of the United States to become directly involved in the Syrian conflict. It seems clear that among those fighting Assad are radical groups that are either linked to or at least sympathetic to Al Qaeda, and the White House certainly doesnít want to inadvertently help their long-term goals.

Syrian state television argued the Israeli missile attacks proved the rebels are supported by an American-Israeli conspiracy designed to punish Assad for supporting Palestinians and opposing Western policies in the Middle East. Assadís critics, meanwhile, contrasted his failure to prevent the missile strikes with his success in killing Syrian civilians.

In times of war, escalation is a fearsome word but get used to it. This war just keeps getting bigger.